Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the burden and does well: it discloses that values are returned as written (no normalization/coercion) and that no validation is performed. It does not state what happens when both or neither of the optional inputs are supplied, nor how malformed XML/PDF is reported.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the verb and output shape, then formats, then usage guidance — a logical order with no filler. The field enumeration is slightly long but every item maps to real return content, so little is wasted.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

No output schema exists, so the description appropriately lists the returned fields and states the parsing-only (non-validating) contract. The remaining gap is the input-selection rule (one of xml/pdf_base64) and failure behavior for unsupported or malformed documents.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 0%, so the description must compensate — and it does, naming the exact formats each parameter accepts (UBL 2.1 Invoice/CreditNote, UN/CEFACT CII XML incl. XRechnung/Peppol BIS 3/Factur-X, and a ZUGFeRD/Factur-X PDF as base64). It omits that at least one input is effectively required and any precedence rule when both are provided.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (read/parse) plus the resource (incoming EU e-invoice) and enumerates the normalized output shape (seller, buyer, dates, totals, VAT breakdown, lines, attachments). It is clearly distinguishable from siblings like validate_einvoice and create_einvoice.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives an explicit trigger ('Use when asked to read, extract or book a received e-invoice') and an explicit exclusion with the named alternative ('does NOT validate it — use validate_einvoice for that'). The two accepted input routes are also named, so an agent knows which parameter to pick.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.